Syngas (mixtures of hydrogen and carbon monoxide) can be readily produced from either coal or methane (natural gas) by methods well known in the art and widely commercially practiced around the world. A number of well-known industrial processes use syngas for producing various oxygenated organic chemicals. The Fischer-Tropsch catalytic process for catalytically producing hydrocarbons from syngas was initially discovered and developed in the 1920's, and was used in South Africa for many years to produce gasoline range hydrocarbons as automotive fuels. The catalysts typically comprised iron or cobalt supported on alumina or titania, and promoters, like rhenium, zirconium, manganese, and the like were sometimes used with cobalt catalysts, to improve various aspects of catalytic performance. The products were typically gasoline-range hydrocarbon liquids having six or more carbon atoms, along with heavier hydrocarbon products.
More recently however, the Fischer-Tropsch process has been increasingly focused on and developed as methods for preparing the heavier hydrocarbons suitable for use as diesel fuels, and/or waxy hydrocarbon molecules suitable for conversion to clean, efficient lubricants.
In modern oil refineries, lower molecular weight C1-C5 hydrocarbons (paraffins and/or olefins) are typically obtained in limited amounts from natural gas condensates and/or petroleum distillates, and are in high demand for conversion (by well-known refinery processes such as steam cracking) to high value lower olefins such as ethylene, propylene, and butenes, which are used in many types of applications, especially as monomers for making plastics.
Accordingly, there remains a long-term market need for new and improved methods for producing increased amounts of lower molecular weight C1-C5 hydrocarbons from non-petroleum feedstocks. Catalysts and methods useful for the production of C1-C5 hydrocarbons from syngas are described herein.